Overview
This lecture explains Public Key Infrastructure (PKI), symmetric and asymmetric encryption, and how digital certificates and key management work in organizations.
Public Key Infrastructure (PKI)
- PKI refers to policies, procedures, hardware, and software for managing digital certificates.
- PKI handles creating, distributing, storing, revoking, and managing digital certificates.
- PKI is often associated with certificate authorities (CAs) that help establish trust between users and devices.
Symmetric Encryption
- Symmetric encryption uses one key for both encryption and decryption of data.
- This key must be kept secret and shared between all parties needing decryption access.
- Managing keys becomes difficult as the number of users increases.
- Symmetric encryption is fast and efficient, making it widely used despite scalability challenges.
- It's also called a secret key algorithm or shared secret encryption.
Asymmetric Encryption
- Asymmetric encryption uses two mathematically related keys: a public key and a private key.
- The public key is shared openly; the private key is kept secret by its owner.
- Data encrypted with the public key can only be decrypted with the private key.
- The mathematical relationship between keys prevents deriving the private key from the public key.
- Key pairs are created simultaneously, often involving randomization and large prime numbers.
Public/Private Key Usage Example
- Users generate a public/private key pair; the public key is shared, the private key is kept secure.
- To send encrypted messages, someone uses the recipient’s public key to encrypt, and only the private key can decrypt it.
- Private keys are often password-protected for added security.
Key Management in Organizations
- Individuals manage their own keys in small settings, but larger organizations require more robust key management solutions.
- Key escrow allows a third party to securely store private keys in case access is needed later.
- Escrow enables data recovery if a user leaves or is unavailable.
- Sometimes, organizations must hand over private keys to maintain business continuity.
Key Terms & Definitions
- Public Key Infrastructure (PKI) — System for managing digital certificates and encryption keys.
- Symmetric Encryption — Encryption method using the same key for both encrypting and decrypting data.
- Asymmetric Encryption — Uses a pair of mathematically related keys (public and private) for encryption and decryption.
- Certificate Authority (CA) — Trusted organization that issues and manages digital certificates.
- Key Escrow — Process where a third party holds encryption keys for backup or recovery purposes.
Action Items / Next Steps
- Review how symmetric and asymmetric encryption are used together in real-world systems.
- Understand the roles of PKI and CAs for trusting digital identities.